When you're the sixth richest person in the world, you buy stuff. In the case of Mark Zuckerberg, the billionaire plunked down some of his estimated $51.7 billion stash and picked up a lovely 700-acre piece of property on the lovely Hawaiian island of Kaua'i in 2014. Fast forward to three days ago when Hike Kaua'i With Me sent out this photo, revealing Zuck's first big step with his big backyard: